Low cost high efficiency ice machine

ABSTRACT

Disclosed are ice making machines which use aluminum as an alternative to copper in the ice making machine evaporator and also use an alternate coolant/refrigerant specifically targeted to provide improved heat transfer transport properties and higher heat capacitance than conventional HFC coolant/refrigerants. Optionally, rotary compressors are used in place of conventional reciprocating compressors, further enhancing performance for the ice making machine. The disclosed ice making machines maintain high efficiency and ice output, and provide equal or better energy efficiency than comparative ice making machines. At the same time, savings are realized in the material cost for the evaporator, and resulting from the combined effects of lower density and lower metal cost/unit weight offered by aluminum as compared to copper.

CROSS-REFERENCED APPLICATION

This application claims priority to U.S. Provisional Application No.61/596,760, filed on Feb. 9, 2012, which is incorporated herein in itsentirety by reference thereto.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates, in general, to ice making machines and,more particularly, to ice making machines using a different type ofcompressor, along with a combination of aluminum as an alternative tocopper in the evaporator as well as an alternate coolant/refrigerantspecifically targeted to provide improved heat transfer transportproperties and higher heat capacitance than conventional HFCcoolant/refrigerants. The resulting ice making machines maintain highefficiency and ice output for a given size of ice making machine, andprovide equal or better energy efficiency than similarly-sizedconventional, currently used ice making machines, while realizing thesavings in material cost for the evaporator resulting from the combinedeffects of lower density, lower metal cost and lower weight per unitoffered by aluminum as compared to copper that is generally used inevaporators of similarly-sized, conventional and currently used icemaking machines.

2. Discussion of the Background Art

Ice making machines are in widespread use for supplying cube ice incommercial operations. Typically, ice making machines produce a largequantity of ice by flowing water over a large chilled surface. Thechilled surface is thermally coupled to evaporator coils that are, inturn, coupled to a refrigeration system. The chilled plate, orevaporator, usually contains a large number of indentations on itssurface where water flowing over the surface can collect. Typically, theindentations are die-formed recesses within a metal plate having highthermal conductivity. As water flows over the indentations, it freezesinto ice.

To harvest the ice, the evaporator is heated by hot vapor flowingthrough the evaporator coils. The evaporator plate is warmed to atemperature sufficient to harvest the ice from the evaporator. Oncefreed from the evaporator surface, a large quantity of ice cubes areproduced, which fall into an ice storage bin. The ice cubes produced bya typical ice making machine are square or rectangular in shape and havea somewhat thin profile. Rather than having a three-dimensional cubeshape, the ice cubes are often tile-shaped and have small height towidth and length ratios/aspects.

Typically, copper is used as the base material for a grid styleevaporator used in a conventional ice making machine. Also typically,HFC-type coolant/refrigerants, such as R-404A and 134A, are used inconventional machines. The combination of copper as the evaporatormaterial and the conventional HFC-type coolant/refrigerants has becomestandard in the industry due, in part, to the excellent thermalconductivity of copper and readily available supply of compressors forR-404A and R-134A. Copper is, however, more dense than some possiblealternatives, and is increasingly expensive. These two characteristicsresult in ice making machines which are unduly weighty and expensive.

Alternatives to copper do exist. However, other metals having highthermal conductivity on a par with copper are typically denser andhigher cost/lb. than copper (silver and gold are two examples) and donot represent a weight/cost reduction opportunity. Aluminum in theoryrepresents an alternative material to copper for use in an ice makingmachine evaporator, but its lower thermal conductivity and higher heatcapacitance properties would cause a loss in performance for the icemaking machine. The lower thermal conductivity of aluminum would causethe refrigeration system to work harder during the freeze cycle due to alarger temperature difference across the aluminum evaporator metal.During the harvest cycle, the combined effects of lower thermalconductivity and higher heat capacitance (poor thermal diffusivity)would cause a slower rate of warming for the aluminum evaporatorcompared to copper. The combined effects of these two characteristicswould ultimately translate to lower ice production due to the longerharvest cycle and a subsequent penalty on overall cycle efficiency whenaluminum is considered as the base material for an evaporator. Tocompensate for the lower thermodynamic performance of aluminum as theevaporator metal, it is possible in theory to change the specificationsof the compressor to improve its capacity and efficiency, or to enlargethe surface area of the evaporator to add heat transfer capability, butthese modifications would add cost and may increase the size and weightof the ice making machine itself. Any increase in size would a hindranceto the use of such an ice making machine in commercial establishmentssuch as fast food restaurants because only a certain square footage canbe allotted to the ice making machine.

Rotary compressors have not been previously employed in ice makingmachines. Rotary compressors are fundamentally different from thehermetic reciprocating and scroll compressors that have been used incommercial ice making machines in two ways: 1) the gas volume inside thecompressor shell is at the high side pressure for the system cycle witha rotary compressor, instead of the low side pressure found in the caseof reciprocating or scroll compressors, and 2) the suction gas entersdirectly into the compression chamber of the rotary compressor, insteadof the indirect entry into the compressor shell volume that is employedin the case of hermetic reciprocating compressors. These differenceshave historically been viewed as a barrier to the application of arotary compressor to a commercial ice making machine. R-410Acoolant/refrigerant has not been used in commercial ice making machinesdue to concerns over discharge gas temperature and higher operatingpressure, without proper consideration of the benefits provided by itssuperior transport properties.

SUMMARY

Thus, present disclosure provides an ice making machine which canutilize a lower cost alternative to copper as the base material in anevaporator.

The present disclosure also provides for the first time employing arotary compressor as the work input to the vapor compression cycle forthe ice making machine without any loss of reliability or properfunction.

The present disclosure also provides an ice making machine whichutilizes a lower cost alternative to copper in the evaporator, yetmaintains the ice production through a comparatively equal harvest cycleand overall cycle efficiency in the production as compared to when acopper evaporator is used.

The present disclosure further provides an ice making machine which canprovide a lower cost alternative to copper as the base material in theevaporator and provide a lighter weight ice making machine.

The present disclosure still further provides an ice making machinewhich matches the output of conventional ice making machines usingcopper as the evaporator, but at equal or better energy efficiency.

Finally, the present disclosure provides for maintaining the samegeometry—overall height, width, and depth—for the evaporator assembly,and also the spacing for the partition strips that form the cube cellsin a grid style evaporator, to maintain the overall physical size forthe ice making machine cabinet, and also provide the same size cube tothe end consumer of the ice. These are important to the success of thesubstitution of aluminum for copper, since there is value associatedwith the physical space occupied by the ice making machine as well asvalue associated with the cube dimensions and weight.

The above and other advantages are met through applicant's presentdisclosure wherein a modified ice making machine has been developedwhich employs a rotary compressor and uses aluminum as the evaporatorbase material. The reliable application of rotary compressors, and theuse of aluminum in an evaporator while keeping the same geometry of icemaking machine and ice cube as with a copper evaporator, yet maintainingice cube harvest, cycle efficiency and energy use, has been accomplishedthrough applicant's novel approach.

In one of the embodiments of the present disclosure, there is providedan alternate approach to coolants for use in an ice making machine,which is to select a coolant/refrigerant that has improved thermaltransport properties. The key transport properties of interest for theice making machine evaporator are the two phase heat transfercoefficient for both evaporation (freeze cycle) and condensation(harvest cycle), and the thermal conductivity for the vapor and liquidphases. By improving the heat transfer between the coolant/refrigerantand the evaporator, the temperature difference is reduced, and the rateof heat transfer during harvest can be increased. These effects offsetthe impact of the change in metal properties when using aluminum for theevaporator. The end result is an ice making machine that is lower incost, but without any loss in capacity or efficiency and without anyincrease in overall physical size of the ice making machine.

In an additional embodiment of the present disclosure, there is providedan ice making machine wherein the selection of the compressor is basedon the higher operating pressure and higher volumetric capacityassociated with the selected coolant/refrigerant(s) having improvedthermal transport properties. While it is possible to use smallerdisplacement versions of hermetic reciprocating compressors with thesecoolant/refrigerants, the compressor shell and internal mechanical partsmust be redesigned to accommodate the higher pressure and forcesresulting from the selected coolant/refrigerant(s). Preferably andoptionally, rotary compressors that employ a rolling piston for thevapor compression process are used in the present disclosure. These havespecific advantages over hermetically sealed piston-type reciprocatingcompressors when used with the selected coolant/refrigerant(s). Thesmaller dead volume in the compression space and smaller leakage pathsfor rotary compressors reduce the impact of the higher density andworking pressure on the efficiency of the compressor. The smallercompressor shell, due to the more compact compression mechanism, alsoreduces the impact of the higher working pressure on the compressorshell material cost.

In yet another embodiment of the present disclosure, the operating cyclefor the ice making machine has been optimized through the sizing of theheat exchangers employed in the thermodynamic cycle, most notably thesuction-liquid heat exchanger (SLHX), along with the setting of thethermal expansion valve, and coolant/refrigerant charge, to ensure therotary compressor does not experience a quantity of liquidcoolant/refrigerant entering the suction port during the harvest cycleof the ice making machine when hot gas is provided to the evaporator.This also ensures that the suction gas condition during the freeze cyclehas low enough coolant/refrigerant enthalpy to control the dischargetemperature of the coolant/refrigerant(s) (e.g., R-410A or R-32) withinthe operating limits of the rotary compressor.

Thus, in one of its specific embodiments, the present disclosureprovides an ice making machine comprising: a coolant/refrigerant systemcomprising a coolant/refrigerant, a compressor, a condenser, anevaporator, an expansion device, a suction-liquid heat exchanger, a hotgas valve for directing hot gases from the compressor to the evaporator,and interconnecting lines therefor, wherein the compressor is a rollingpiston type device.

And, in another of its specific embodiments, the present disclosureprovides an ice making machine comprising: a coolant/refrigerant systemcomprising a coolant/refrigerant, a compressor, a condenser, anevaporator, an expansion device, a suction-liquid heat exchanger, a hotgas valve for directing hot gases from the compressor to the evaporator,and interconnecting lines therefor, wherein the evaporator is comprisedof aluminum, the coolant/refrigerant has a forced convection heattransfer coefficient of at least about 1000 Btu/hr.-ft.-F, a liquidthermal conductivity of at least about 0.060 Btu/hr.-ft.-F at 0° F., anda volumetric refrigeration capacity of at least about 75 Btu/ft.³, andthe compressor is a rotary compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, features and advantages of this disclosure result fromthe following description of an embodiment using the drawing, in which:

FIG. 1 is a schematic drawing of an ice making machine; and

FIG. 2 is a graph showing comparisons in ice making production of icemaking machines of the present disclosure compared to state of the artice making machines.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 shows a general flow scheme of a coolant/refrigerant system of anice making machine such as those which are the subject of the presentdisclosure. In FIG. 1, there is closed coolant/refrigerant system 10containing coolant/refrigerant in which compressor 20 is filled to anappropriate level with a suitable gas coolant/refrigerant. Compressor 20increases the pressure of, and thus the temperature of, thecoolant/refrigerant. The coolant/refrigerant exits the compressor 20 andis passed along, due to the compressor 20 pressurizing the entiresystem, to condenser 30 where the high pressure coolant/refrigerantgives up its heat and liquefies. The high pressure coolant/refrigerantgives up its heat through ambient heat exchange with the environment,occurring as the high pressure coolant/refrigerant, passes through theserpentine-like coils of the condenser. The coolant/refrigerant leavesthe condenser as a high pressure liquid and passes through thesuction-liquid heat exchanger (SLHX) where temperature and enthalpy ofthe liquid coolant/refrigerant leaving the condenser is further reducedthrough heat exchange with the coolant/refrigerant leaving the icemaking machine evaporator. The liquid coolant/refrigerant then flows toexpansion valve 40. Expansion valve 40 can be said to have a “condenser”side (on the side of the system where the flow of coolant/refrigerantcomes from the condenser) and an “evaporator” side (on the side of thesystem where the flow of coolant/refrigerant goes to the evaporator).Because the high pressure liquid coolant/refrigerant is urged throughexpansion valve 40 due to the pressure drop across expansion valve 40,the liquid coolant/refrigerant immediately boils, gains heat fromevaporator 50, and cools evaporator 50. At the surface of evaporator 50there are located a plurality of cells (not shown) into which waterflows and freezes in thin layers repeatedly, yielding ice cubes ofsubstantially uniform dimension. At intervals determined by electronicsensors (not shown), hot gas solenoid valve 60 is opened to direct hotdischarge gas from compressor 20 to evaporator 50 inlet, warmingevaporator 50 to a temperature sufficient to melt the ice at theinterface between the ice and evaporator 50 surface, which releases theslab of ice formed on evaporator 50 into a storage bin situated belowthe ice making machine. After passing through evaporator 50, thecoolant/refrigerant gas flows through the SLHX, where it is warmed bythe liquid exiting condenser 30, and then flows to the suction inlet ofcompressor 20.

Evaporator 50 of the present disclosure, as mentioned, can be made ofaluminum, or an alloy comprising aluminum. Within the meaning of“aluminum”, it is possible to use any of the common alloy families forevaporator 30. The most preferred alloys are the 3000 series, due tocost and brazing performance, the 6000 series, due to mechanicalstrength for sheet material, and the 4000 series for die cast material.The selection of the alloy will depend upon the particular performancecharacteristics desired and the manufacturing performance anticipated.For brazed evaporators 50, characteristics which may be important in anyparticular application include, but are not limited to: bonding of allpartition edges to the pan (gap control), post-brazing surface chemistrycompatible with the plating/coating (if plating/coating will beundertaken), durability of brazed joints over a lifetime of freeze-thawcycles, dimensional control over grid surfaces, and process controllimits. Evaporator 50 may also be cast aluminum or cast aluminum alloy.Cast evaporators 50 have the benefit of needing fewer manufacture andproduction steps than brazed evaporators 50, but have disadvantages incontrolling the thickness of the cast aluminum. Also, cast aluminumevaporators 50 often require additives to improve flow and movement ofthe molten aluminum into the casting mold, and some of these additiveshave the characteristic of being insulators which, in turn, sometimesinhibit or restrict heat transfer characteristics of evaporator 50. Atthe present time, brazed evaporators 50 are preferred, and the brazingmaterial is preferably an aluminum alloy having a melt temperature about50° C. below the melt temperature of the base aluminum evaporator 50.Typical preferred aluminum brazing alloys are in the aluminum 4000series of alloys. These alloys have a relatively high percentage ofsilicon as an alloying element that reduces the melting temperature ofthe alloy. There is a relatively narrow window around 1100° F. for thebrazing temperature of these alloys. The temperature must be controlledwithin this narrow window during the brazing process so that the meltingtemperature of the base aluminum material being brazed is not exceeded.The composition and properties of a typical brazing alloy are shownbelow. This material is available clad onto sheet aluminum, as a foil orin paste form. The composition of the presently preferred brazingmaterial is a 4047 aluminum alloy, having an aluminum content of betweenabout 87%-89%, a silicon content of about 11%-13%, a content of otherminor elements (each) of about 0.05%, maximum, and a content of otherminor elements (total) of about 0.15%, maximum. The physical propertiesof an alloy of this type are: melting point, about 1070° F. (577° C.), aflow point of about 1080° F. (582° C.), a brazing range of between about1080° F.-1120° F. (582° C.-604° C.), a specific gravity of about 2.66,and a density of about 0.096 lbs/in³.

Evaporator 50 may be left uncoated, or may be coated for use. Forcoated/plated aluminum evaporators 50, development of surface chemistryspecifications may be useful, depending upon the application, including:the surface preparation process prior to the plating or coating process,the plating/coating formulation and bath chemistry, the process stepsand process parameter control limits, an analysis of plating/coatingfailures during durability testing, and FDA approval for thecoating/plating, if needed. Among the coatings useful for evaporator 50are nickel coatings, preferably electroless nickel coatings, and organicpolymer based coatings. Electroless nickel or other metallic electrolesscoatings are known in the art, and any such coating may be selectedbased upon the application in mind. When selecting an electroless nickelcoating, the factors mentioned above should be kept in mind. The organicpolymer based coatings useful in the present disclosure are also knownin the art, and are sometimes referred to as “electrocoating”.Electrocoating is a method of applying various types of coating toelectrically conductive surfaces. The coating constituents utilized aredispersed in water and contained in a special bath. After cleaning andany other necessary preparation, the parts to be coated are immersed inthe bath and the coating is applied by the action of an electriccurrent. After coating to the required thickness, the parts are removedfrom the bath and excess coating is rinsed off and recycled. The appliedcoating is hardened (for example by baking at elevated temperature) toachieve its performance properties. Among the coatings useful in thislatter approach are organic polymer based coatings based uponfluorine-based polymers, which may also contain a ceramic oxide. Suchcoatings may be obtained from known suppliers, such as LVH CoatingsLtd., Station Road, Coleshill, UK.

Coolant/refrigerants based on R-32, due to the excellent transportproperties and specific capacity of R-32, provide the targetcharacteristics of improved thermal transport properties of interest forevaporator 50. As mentioned above, these characteristics include the twophase heat transfer coefficient for both evaporation (freeze cycle) andcondensation (harvest cycle), and the specific heat for the vapor andliquid phases. Difluoromethane, also called HFC-32 or R-32, is anorganic compound of the dihalogenoalkane variety. It is based onmethane, except that two of the four hydrogen atoms have been replacedby fluorine atoms. Hence the formula is CH₂F₂ instead of CH₄ for normalmethane. Difluoromethane is a coolant/refrigerant that has zero ozonedepletion potential. Difluoromethane in azeotropic (50%/50%weight/weight) mixture with pentafluoroethane (R-125) is known asR-410A, a common replacement for various chlorofluorocarbons (CFCs) innew coolant/refrigerant systems, especially for air-conditioning. Theazeotropic mixture of difluoromethane with pentafluoroethane (R-125) andtetrafluoroethane (R-134A) is known as R-407A through R-407E dependingon the actual compositional make-up of the mixture. Other mixtures basedon R-32 are known as well. R-410A is the current commercially availablepreferred option, but due to expected changes in safety classificationsand building codes, other blends involving R-32 and pure R-32 may becomesuitable choices.

As noted, there can be a number of coolant/refrigerant blends thatemploy R-32 as a primary ingredient to provide the required transportproperties to achieve target ice production capacity and energyefficiency. The key parameters which should be considered and which thecoolant/refrigerant should have are a forced convection heat transfercoefficient of at least about 1000 Btu/hr.-ft.²-F, a liquid thermalconductivity of at least about 0.060 Btu/hr.-ft.-F at 0° F., and avolumetric refrigeration capacity of at least 75 Btu/ft.³. R-410A has aforced convection heat transfer coefficient of 1100, a liquid thermalconductivity of 0.063 and a volumetric refrigeration capacity of 75Btu/ft.³. The coolant/refrigerant should also be a pure component or anazeotropic mixture to avoid any performance degradation that may occurin evaporator 50 due to the temperature glide of a zoetrope as thecoolant/refrigerant evaporates or condenses.

The selection of R-410A, R-32, or other blended coolant/refrigerantsbased on R-32, requires selection of a compressor based on the higheroperating pressure and higher volumetric capacity associated with R-410Aor other R-32 based coolant/refrigerants. While it is possible to usesmaller displacement versions of hermetic reciprocating compressors withR-410A, if the compressor shell and internal mechanical parts areredesigned to accommodate the higher pressure and forces resulting fromR-410A when compared to the conventional industry choice of R-404A forcommercial ice making machines, rotary compressors that employ a rollingpiston for the vapor compression process have specific advantages foruse with R-410A or R32 over reciprocating compressors. The smaller deadvolume in the compression space and smaller leakage paths for rotarycompressors reduce the impact of the higher density and working pressureon the efficiency of the compressor. The smaller compressor shell, dueto the more compact compression mechanism, reduces the impact of thehigher working pressure on the compressor shell material cost. Theintroduction of a rotary compressor into a commercial ice making machineenables a cost efficient and reliable refrigeration system. Selection ofthe particular rotary compressor will depend upon the size and capacityof the ice making machine. The reliable application of rotarycompressors to an ice making machine requires precise control of theamount of liquid coolant/refrigerant entering the compressor suctionport during the harvest cycle and the degree of superheat entering thecompressor suction port during the freeze cycle.

Alternates to a rotary compressor include scroll compressors, andreciprocating compressors. Scroll compressors eliminate the dead volumein the compression space, but have greater leakage path relative to thedisplacement than a rotary compressor, and in the smaller sizes suitablefor the majority of the ice making machines, are less efficient and moreexpensive to manufacture. As noted above, reciprocating compressors aresignificantly less efficient due to the relative high pressure ratio foran ice making machine combined with the inherent dead volume in thecompressor. There are also discharge temperature limitations withreciprocating compressors due to the high pressure ratio and lowspecific heat of vapor for R-410A.

Description of the Preferred Embodiments

The disclosure will now be described with reference to the followingexamples. These examples are for the purpose of more fully explaining toone of skill in the art the practice of the present disclosure. Theseexamples are not limiting to the full scope of the present disclosure asexplained above and as encompassed in the claims which follow.

The following examples compare the ice making production and energyusage of the ice making machine of the present disclosure, using analuminum evaporator made from 3000 series aluminum with brazedconstruction, and electroless nickel plating, R-410A coolant/refrigerantand a rotary compressor (Rotary 124-YV6A7), to the same general model ofice making machine not having the modifications taught by the presentdisclosure. The comparative ice making machines not having themodifications of the present disclosure use a copper evaporator, aR-404A coolant/refrigerant and a reciprocal piston compressor (ManitowocSY0452A-161 Baseline). Ice was produced at various air/water temperatureproduction protocols. For air temperatures of 50° F. and 70° F., thewater temperature was 50° F.; for air temperature of 90° F., the watertemperature was 70° F.; and for air temperature of 110° F., the watertemperature was 90° F.

The results of the above comparisons are shown in the graph in FIG. 2.At the temperature combination of 50° F./50° F., the ice making machineaccording to the present disclosure produced 458 lbs. of ice per 24hours, compared to 440 lbs. of ice for the comparative ice makingmachine. At the temperature combination of 70° F./50° F., the ice makingmachine according to the present disclosure produced 450 lbs. of ice per24 hours, compared to 442 lbs. of ice for the comparative ice makingmachine. At the temperature combination of 90° F./70° F., the ice makingmachine according to the present disclosure produced 378 lbs. of ice per24 hours, compared to 346 lbs. of ice for the comparative ice makingmachine. At the temperature combination of 110° F./90° F., the icemaking machine according to the present disclosure produced 291 lbs. ofice per 24 hours, compared to 267 lbs. of ice for the comparative makingmachine.

In the above detailed description, the specific embodiments of thisdisclosure have been described in connection with its preferredembodiments. However, to the extent that the above description isspecific to a particular embodiment or a particular use of thisdisclosure, this is intended to be illustrative only and merely providesa concise description of the exemplary embodiments. Accordingly, thedisclosure is not limited to the specific embodiments described above,but rather, the disclosure includes all alternatives, modifications, andequivalents falling within the true scope of the appended claims.Various modifications and variations of this disclosure will be obviousto a worker skilled in the art and it is to be understood that suchmodifications and variations are to be included within the purview ofthis application and the spirit and scope of the claims.

What is claimed is:
 1. An ice making machine comprising: acoolant/refrigerant system comprising coolant/refrigerant, a compressor,a condenser, an evaporator, an expansion device, a suction-liquid heatexchanger, a hot gas valve for directing hot gases from the compressorto the evaporator, and interconnecting lines therefor, wherein thecompressor is a rolling piston type device.
 2. An ice making machineaccording to claim 1, wherein the compressor is a rotary rolling pistontype hermetic compressor.
 3. An ice making machine comprising: acoolant/refrigerant system comprising coolant/refrigerant, a compressor,a condenser, an evaporator, an expansion device, a suction-liquid heatexchanger, a hot gas valve for directing hot gases from the compressorto the evaporator, and interconnecting lines therefor, wherein thecoolant/refrigerant has a forced convection heat transfer coefficient ofat least about 1000 Btu/hr.-ft.²-F, a liquid thermal conductivity of atleast about 0.060 Btu/hr.-ft.-F at 0° F., and a volumetric refrigerationcapacity of at least about 75 Btu/ft.³
 4. An ice making machineaccording to claim 3, wherein the coolant/refrigerant is comprised ofR-32.
 5. An ice making machine according to claim 3, wherein thecoolant/refrigerant is comprised of R-410-A.
 6. An ice making machinecomprising: a coolant/refrigerant system comprising coolant/refrigerant,a compressor, a condenser, an evaporator, an expansion device, asuction-liquid heat exchanger, a hot gas valve for directing hot gasesfrom the compressor to the evaporator, and interconnecting linestherefor, wherein the evaporator is comprised of aluminum.
 7. An icemaking machine according to claim 6, wherein the evaporator is brazed orcast aluminum.
 8. An ice making machine according to claim 7, whereinthe evaporator is brazed aluminum and is coated.
 9. An ice makingmachine according to claim 8, wherein the evaporator is coated with acoating selected from electroless nickel coating and electrocoatedpolymer coating.
 10. An ice making machine comprising: acoolant/refrigerant system comprising coolant/refrigerant, a compressor,a condenser, an evaporator, an expansion device, a suction-liquid heatexchanger, a hot gas valve for directing hot gases from the compressorto the evaporator, and interconnecting lines therefor, wherein theevaporator is comprised of aluminum, the coolant/refrigerant has aforced convection heat transfer coefficient of at least about 1000Btu/hr.-ft.²-F, a liquid thermal conductivity of at least about 0.060BtuThr.-ft.-F at 0° F., and a volumetric refrigeration capacity of atleast about 75 Btu/ft.³ and the compressor is a rotary compressor. 11.An evaporator for use in an ice making machine, said evaporatorcomprised of coated and brazed aluminum brazed with a brazing materialcomprised of an aluminum alloy having an aluminum content of betweenabout 87%-89% and a silicon content of about 11%-13%, and coated with acoating selected from electroless nickel coating and electrocoatedpolymer coating.
 12. A method of making ice in an ice making machine,said method comprising flowing water over an evaporator comprised ofaluminum, and cooling the evaporator using a coolant/refrigerant havinga forced convection heat transfer coefficient of at least about 1000Btu/hr.-ft.-F, a liquid thermal conductivity of at least about 0.060Btu/hr.-ft.-F at 0° C., and a volumetric refrigeration capacity of atleast about 75 Btu/ft.³.